States of matter (Edexcel IGCSE Chemistry (Modular): Unit 1)

This question is about the three states of matter, solid, liquid and gas.

Solids, liquids and gases can be changed from one state to another.

Use words from the box to complete the sentences.

Each word may be used once, more than once or not at all.

i) The change from solid to liquid is called

(1)

ii) The change from liquid to gas is called

(1)

iii) The change from solid to gas is called

(1)

Describe the arrangement and the movement of particles in a solid.

This question is about ammonium chloride.

Give the formula of the ammonium ion.

Describe a test to show that ammonium chloride contains ammonium ions.

The equation shows the thermal decomposition of ammonium chloride.

NH₄Cl(s)  NH₃(g) + HCl(g)

State what the symbol indicates about this reaction.

The diagram shows the formation of ammonium chloride in a glass tube.

i) Explain how the mean speed of ammonia molecules compares with the mean speed of hydrogen chloride molecules.

(2)

ii) Gas particles travel very quickly. Give two reasons why it takes several minutes for the ammonium chloride to form.

(2)

The boxes list changes that may happen in a laboratory and the names of some changes.

 Draw one straight line from each change to its correct name.

A student has two solids, X and Y.

One of these solids is a pure substance and the other is a mixture.

Describe how the student could identify which solid is pure and which is a mixture by measuring a physical property of each solid.

This question is about states of matter.

Use the words solid, liquid or gas to give the initial and final state of matter for each of the changes listed in the table.

The first one has been done for you.

Particles in a solid are closely packed, arranged in a regular pattern and vibrate about fixed positions.

Describe the arrangement and movement of the particles in a gas.

This question is about states of matter.

The box gives words relating to changes of state. 

Complete the table by giving the correct word from the box for each change of state.

When ammonia gas and hydrogen chloride gas mix, they react together to form a white solid called ammonium chloride.

 The equation for the reaction is

 NH₃ (g) + HCl (g) → NH₄Cl (s)

A teacher soaks a piece of cotton wool in concentrated ammonia solution and another piece of cotton wool in concentrated hydrochloric acid.

The teacher places the two pieces of cotton wool at opposite ends of a glass tube at the same time.

After several minutes, a white ring of solid ammonium chloride forms.

 i) State the name given to the spreading out of gas particles.

(1)

 ii) State how the diagram shows that the particles of ammonia gas are travelling at higher speeds than the particles of hydrogen chloride gas.

 (1)

 iii) Gas particles travel at high speeds.

 Give a reason why the white ring of ammonium chloride takes several minutes to form.

 (1)

 iv) Concentrated ammonia solution and concentrated hydrochloric acid are corrosive.

 Give one safety precaution the teacher should take.

 (1)

Ammonium chloride decomposes in a reversible reaction. The equation for this reaction is

NH₄Cl (s) NH₃ (g) + HCl (g)

State how the equation shows that the reaction is reversible.

Some ammonium chloride is heated gently in a test tube.

The diagram shows the test tube after it has been heated gently for a short time.

i) Identify solid X and the two gases formed in region Y of the test tube.

Solid X ................................................................................................

Gases at Y ..................................................................................................

(2)

ii) Which change of state occurs in the test tube during heating? 

(1)

An experiment involving ammonium chloride can be used to show the process of diffusion.

The diagram shows the apparatus at the start of the experiment.

At the end of the experiment, a white solid forms in the test tube. Explain which position, A, B or C, shows where the white solid forms.

Potassium permanganate is a purple solid that is soluble in water.

A crystal of potassium permanganate is placed in a beaker containing water.

After a short time, the crystal becomes smaller and the liquid at the bottom of the beaker becomes purple.

Which statement explains this observation?

The beaker is left until there is no further change in the appearance of the liquid. 

i) Which statement describes the final appearance of the liquid?

 (1)

ii) Which process causes this change in appearance?

(1)

The formula of potassium permanganate is KMnO₄.

How many different elements are there in potassium permanganate?

Separate: Chemistry Only

The solubility curve for copper(II)sulfate is shown below:

Which of these statements is supported by the graph?

Lead nitrate and potassium iodide react to form the insoluble solid lead iodide. Crystals of lead nitrate and potassium iodide are placed at opposite ends of a container of water. Solid lead iodide forms after several minutes. The diagram shows the container at the start and after several minutes.

Name the two processes that occur before the solid lead iodide forms.

Explain why solid lead iodide takes less time to form when the reaction is repeated using water at a higher temperature.

The formula for lead nitrate is Pb(NO₃)₂

i) Give the number of different elements in lead nitrate.

(1)

ii) Give the charge on the lead ion in Pb(NO₃)₂

(1)

Complete the chemical equation for the reaction between lead nitrate and potassium iodide. 

Pb(NO₃)₂ (aq) + .......... KI (aq) → PbI₂ (s) + .......... KNO₃ (aq)

The table gives the melting and boiling points of four pure substances, W, X, Y and Z.

Use data from the table to answer the questions.

i) Which substance is a gas at 100 °C?

(1)

ii) Which substance is a liquid for the largest range of temperature?

(1)

iii) Which substance is a liquid at 1000 °C and a gas at 2000 °C?

(1)

Substance Y does not conduct electricity when solid but does conduct electricity when molten.

Give the type of bonding in substance Y.

Suggest how the melting point of a pure substance changes when an impurity is added.

Separate: Chemistry Only

This is a method used to measure the solubility of a solid in water:

• add an excess of solid to some water in a boiling tube and stir

• measure the temperature of the saturated solution formed

• weigh an empty evaporating basin

• pour some of the saturated solution into the evaporating basin

• weigh the basin and contents

• heat the evaporating basin to remove all of the water

• weigh the evaporating basin and remaining solid

The table shows the results of an experiment using this method.

Calculate the mass of solid obtained and the mass of water removed.

mass of solid = .............................................................. g mass of water = .............................................................. g

Separate: Chemistry Only

In another experiment, at a different temperature, the mass of solid obtained is 10.5 g and the mass of water removed is 16.8 g. Calculate the solubility of the solid, in g per 100 g of water, at this temperature.

solubility = .............................................................. g per 100 g of water

Separate: Chemistry Only

If the evaporating basin is heated too strongly, some of the solid decomposes to form a gas. Explain how this strong heating would affect the value of the calculated solubility of the solid.

Separate: Chemistry Only

A student investigates the solubility of potassium nitrate in water. She measures the masses of potassium nitrate that dissolve in 25 cm³ of water at different temperatures.

The table shows the student’s results.

One of the results is anomalous.

i) Plot the results on the grid.

(1)

ii) Draw a circle around the anomalous result.

(1)

iii) Ignoring the anomalous result, draw a curve of best fit.

(1)

Separate: Chemistry Only

 Suggest two possible mistakes that could have caused the anomalous result.

1. ..............................................................

2. ..............................................................

Separate: Chemistry Only

Use your graph to find the maximum mass of potassium nitrate that dissolves in 25 cm³ of water at 75 °C.

Show on your graph how you obtained your answer.

   mass = ............................................... g

Separate: Chemistry Only

 Use your graph to calculate the solubility of potassium nitrate in g per 100 g of water at 25 °C. 

[1.0 cm³ of water has a mass of 1.0 g]

solubility = ............................................... g per 100g of water

Separate: Chemistry Only

 This question is about solubility.

The graph shows the solubilities of copper(II) chloride and sodium chloride at different temperatures. 

i) Determine the temperature at which copper(II) chloride and sodium chloride have the same solubility.

 Show on the graph how you obtained your answer.

 (2)

 temperature = .............................. °C

 ii) A saturated solution of copper(II) chloride in 100 g of water is cooled from 40 °C to 10 °C.

 Determine the mass, in grams, of copper(II) chloride that crystallises.

 (2)

 mass of copper(II) chloride = .............................. g

Separate: Chemistry Only

 A student uses this method to determine the solubility of potassium chloride in water at room temperature. 

• record the mass of an empty evaporating basin

• pour some saturated potassium chloride solution into the evaporating basin

• record the mass of the evaporating basin and saturated potassium chloride solution

• heat the evaporating basin to remove all the water

• record the mass of the evaporating basin and the dry potassium chloride

The table shows the student’s results.

 i) Calculate the mass of dry potassium chloride obtained.

 (1)

 mass = .............................. g

 ii) Calculate the mass of water removed.

 (1)

 mass = .............................. g

 iii) Calculate the solubility of potassium chloride in grams per 100 grams of water.

 (2)

 solubility = .............................. g per 100 g of water

 iv) Suggest why the student’s method is not suitable for determining the solubility of hydrated copper(II) sulfate.

 (1)